Power actuator with pilot control



Aug 24, 1954 E. R. SMITH 2,687,044

POWER AOTUATOR WITH PILOT CONTROL Filed April 6, 1953 2 Sheets-Sheet l 1s l\\\\\\\\\\\\\\\\\ a f-IQ- INVENTOR. M EDWIN R. SMHTH.

ATT'Y.

Aug' 24, 1954 E. R. SMITH 2,687,044

POWER AOTUATOR wTTH PILOT CONTROL Filed April 6, 1953 2 Sheets-Sheet 2 INVENTOR. Y EDWIN R SMITH Pa'tentecl Aug. 24, 1954 UNITED STATES PATENT OFFICE POWER ACTUA'ToR Wrri rlio'r1 ooNriioi. Edwinv a. smith; seneca Falls; N. Y., assignof to N. Y., a corporation of Massachusetts' Application April t, 195LS`or`i'a1`No; 3463er" 2 Claims. (CIL `WIL-.388)

IThis invention relates to `a power actuator of the type in which a normally-rotating power or input shaft may bef selectively coupled by a relatively small pilot or control device to drive an output shaft during an operative period determined by the control device. Such power actuators may be required for certain special purposes, such as power steering of a boat or automobile, in which provision must be made for alternative manual operation, if the power actuator for any reason becomes inoperativeI or nona available,

It is the general object of my invention to provide` a power actuator or servo-mechanism to be rendered operative by initial movement of a control shaft, together with an available direct actuating connection between the control shaft and the output shaft; for manualuse if such initial movement of the control shaft is not` productive of the desired results. More' specifically, I provideV a yielding lstmotion connection between the control shaft and the output shaft by which the output shaft may be turned manually if the lost-motion is taken up without providing an effective connection between the input and the output shafts.

My invention further' relates to arrangements and combinations of parts which will be hereinafter described and more particularly pointed out in the appended claims.

A preferred form of the invention is shown in the drawings, in which Fig. 1 is a sectional plan View, taken along the irregular section line I--I in Fig. 2;

Fig, 2 is an end elevation, looking in the direction of the arrow 2 in Fig. l;

Figs. 3, 4 and 5 are detail sectional views, taken along the lines .fl-3, 4 4 and 5-5 in Fig. l; and

Fig. 5 is a perspective view of my improved power actuator but with certain parts omitted for clearness.

Referring to the drawings, I have shown a power actuator which embodies many features 'of the power actuator shown and described in Small Patent No. 2,569,585, patented October 2, 1951, and owned by the present assignee.

This power actuator comprises a casing C provided with bearings for an input shaft IIJ, an output shaft I2 and a control shaft I4. The input shaft I is continuously rotated, and operates through spiral gears I and I6, a pinion I1 (Fig. `1) and a gear I8 to continuously rotate a shaft 20. The gear IB also engages and oppositely rotates an equal gear 22 (Fig, 6) on a parallel 2l. shaft 23 corresponding to the shaftl 20' above named.` V y drurri 25 (Fig. l) is loosely mounted on the shaft 20 and is'c'onnected' thretoby aroll-"away clutch 2S (Fig. 3)". A" gear 30 is also loosely mounted on the shaft 20: and engages' a gear 3| xed on the `control shaft I4. p

I A gear 4D* (Fig. l)` is xed to the output shaft f2 and engages an"l equal lgear 4I loose on the shaft 2D'. Aspiral'band 44 (Fig. 6) is connected at`-` one* end to"l the gear 30 previously described and' at itsopposite endto a part associatedV with die gear 4r. y,

`If the gear 3011s rotated byany movement of the" control' shaft I4', the'band 44] will be tight'- eiied onl the continuouslyerotated drum 25, and the-output shaft I2 will then be rotated through the hand 44 and gears" 4U and 4l` until the bandi r4 is loosened bysuoh rotation.

The foregoing description of the driving connectionthroughthegear I'and shaft 2|J` (Fig. 6) applie's equally to" the identical butI revers'elydisposed driving connection through the gear 22 and shaft 23. The direction of rotation of the output shaft I2 corresponds to the direction of rotation of the control shaft I4, when the control shaft is displaced in either direction.

For a more detailed description of the construction and operation of the mechanism thus far described, reference is made to the Small patent previously identified.

The shafts I2 and I4 are aligned as shown in Fig. 1 but are only connected through a yielding coupling best shown in Figs. l, 4 and 5.

The hub portion 40a of the gear 40 on the output shaft I2 is recessed at 59 (Fig. 5) and is provided with oppositely-disposed and inwardly-projecting lugs 5I. A coupling member 55 is mounted on the control shaft I4 (Fig. 5) which also supports the gear 3l, and the member 55 extends loosely into the recess 50 in the hub 40a. The member 55 has oppositely-disposed recesses 56 which loosely receive the lugs 5I on the hub 40a but with a predetermined amount of lostmotion.

The coupling member 55 is also provided with oppositely-disposed lugs 58` and with segmental recesses 59 to receive short coil springs 60. Each spring 60 engages a lug 58 at one end and a lug 5I at the opposite end as clearly shown in Fig. 4, and the joint action of the four springs normally centers the lugs 5I in the recesses 56 as shown in Fig. 5.

With this construction, a slight movement of the control shaft I4 in either direction is permitted by the yielding lost-motion connection before a direct connection between the control shafts Id and the output shaft I2 can be established. This slight movement tightens the band 44 by the action of the gears 3l and 30, and power is then transmitted from the input shaft l! through the gears 4l and' 40 to the output shaft l2.

If, however, the limited lost-motion available between the coupling member 55 and the hub Mia.

does not establish a driving connection through the spring mi to the input shaft I0, `then the output shaft I2 may be turned directlyby continued manual application of power to the control shaft id. Such alternative operation is particularly desirable where the output shaft l2 connects to the steering mechanism for a boat or automobile which absolutely7 must respond to movement of the control shaft Hl, as this shaft would commonly be direct connected to the steering wheel.

The roller clutches 26 are provided so that the drums 25 will be free of the shaft 2D or 23 whenever a shaft is rotated backward during a drive through the opposite drum unit.

I have thus provided a simple power actuator capable of general application but having exceptional advantages under certain special conditions. I also provide an actuator in which the output shaft may be directly rotated from the control shaft at any time and without any shifting of connections or any delay in operation.

Having thus described my invention and the advantages thereof, I do not wish to be limited to the details herein disclosed, otherwise than as set forth in the claims, but what I claim is:

l. In a power actuator, a control shaft, an output shaft aligned therewith, a limited lostmotion connection between said shafts, a power shaft, means to rotate said power shaft in one direction only, a servo-connection between said power shaft and said output shaft which includes a countershaft, a gear fixed thereon, a gear loose thereon and connected to drive said output shaft, a drum loose on said countershaft, a one-way clutch for said drum, a helical spring encircling said drum and having one end secured to said loose gear, and a spring-tightening connection from said control shaft to the opposite end of said spring, and said clutch normally rotating said drum with said countershaft but permitting said drum to be rotated freely on said shaft when independently turned ahead more rapidly ,than said shaft is rotated.

2. In a power actuator, a control shaft, an

loutput shaft aligned therewith, a limited lostmotion connection between said shafts, a power shaft, means to rotate said power shaft in one direction only, a servo-connection between said power shaft and said output shaft which includes two countershafts, a gear fixed to each countershaft, a gear loose on each countershaft and connected to rotate said output shaft in opposite directions, a drum loose on each countershaft, oppositely-disposed one-way clutches for said drums, oppositely-wound helical springs encircling said drums and each having one end secured to the associated loose gear, and a springtightening connection from the other end of each spring to the controly shaft, and said clutches normally rotating said drums with said countershafts but permitting each drum to be rotated freely on its shaft when independently turned ahead more rapidly than said shaft is rotated.

References Cited in the le of this patent UNITED STATES PATENTS Number Name A Date Re. 23,550 Staude Sept. 9, 1952 Re. 23,673 Penrose June 30, 1953 2,569,585 Small Oct. 2, 1951 2,569,586 Small Oct. 2, 1951 

